Thioindoxyl couplers for color photography



Patented Sept. 14, 1948 THIINDOXYL COUPLER/S FOR COLOR PHOTOGRAPHY Fritz W. H. Mueller and Abraham Bavley, Binghamton, N. Y., assignors toGeneral Aniline & Film Corporation, New York, N. Y., a corporation of Delaware No Drawing. Application January 25, 1945, Serial No. 574,619

This invention relates to the production of colcred photographic images by color-forming development, and more particularly to arylaldehyde derivatives bridged by a single methine chain as color-forming couplers therefor.

It is known that compounds containing methylenegroups whose ,hydrogens are activated by other substituents inthe molecu e, such as carbonyl (CO) or nitrile (CN), readily combine directly with arylnitroso compounds or indirectly with primary aromatic amines in the presence of an oxidizingagent. through intermediate oxidize.- tion products, to form azomethine dyes. For example, 1-phenyl-3-methyl-5-pyrazolone reacts with p-nitroso-dimethylaniline tq'form the ammethine dye, 1-phenyl-4-dimethyl-aminophenylimino-3-methyl-5-pyrazolone. Alternatively, the same dye results from the reaction of the above mentioned :pyrazolone with p-aminodimethylaniline in the presence of an oxidizing agent such as, for example, potassium persulfate.

The ability of these so-called couplingcompounds to react with primary aromaticamines in the presence of oxidizing agents forms the basis of color development in photographic subtractive color processes, in which the amine developing agent becomes oxidized locally with the formation of the silver image and immediately reacts with .thejcoupli'ng compound to form an, azomethine dye image insitu with the developed silver image f it 7 Arylaldehyde derivatives which are linked together by a single methine group and employed as filter and anti-halation dyes are already known, Compounds of this category are illustrated, for example, in United States Patent 2,036,546. It will be noted that the arylaldehyde derivatives referred to in this patent are employed as filter and anti-halation dyes which can be complete y and permanently decolorized within a short time in photographic developin solutions containing sodium sulfite or sodium bisulfite.

It is an object of the present invention to provide a new class of color-formers for the production of cyan and magenta images by color-forming development.

A further object is to provide photographic emulsions and developer solutions Which contain a newclass of color-formers for producing cyan and magenta images in situ with photographic images.

A still further object is to provide finished photographs which contain stable dye images.

Other objects will be apparent by reference to 6 Claims.

2 the following specification in which its preferred details and embodiments are described.

This invention is based on the discovery that arylaldehyde derivatives which are linked to-' gether by a single methine (CH=) chain in the reactive coupling position normally occupied by the arylimino group during azomethine dye formation will react in colon-forming development with the oxidation product of the developer in the absence of sodium sulfite or sodium bisulfite, in the usual manner, toformdyeimages. It has been found that the methine group of the color-former is displaced by'the arylamino group during dye image formation. This discovery is surprising and wholly unexpected since, in general, methin linkages are not readily displaced by other groups in the absence of a reducing agent.

The a-rylaldehyde derivatives bridged by a single methine chain of the present invention, are represented by the following general formula:

wherein It represents a grouping of atoms nectessary to complete a five-membered or six-membered heterocyclic nucleus, e, g., oxythionaphthene, methyloxythionaphthene, coumaranon, oxyselenonaphthene, thlobarbituric acid, barbituric acid, oxindole, homophthalimide thiooxazoledione, isohydantoin, rhodanine, selenazolonethione and the like, R1 represents an arc: matic group such as aryl, e. g., phenylnaphthyl, anthryl and the like. Said aryl group may be substituted by a radical such as an alkyl group, e. g., methyLethyl, propyl, butyl, octyl, decyl, octadecyl, stearyl, or any otheralkyl or alkylamino radical containing up to 24 carbon atoms, amino groups, e. g., primary amino, secondary amino, such as methylamino, phenylamino and the like, or tertiary amino such as dimethylamino, diphenylamino, etc., sulfamino or solubilizing groups such as sulfonic or carboxylic acid groups, and X represents either sulfur, oxygen, selenium, benzo or acarbonyl radical.

These compounds are readily prepared by condensing molecular proportions of an aromatic or cyclic aldehyde with a five-membered or sixmembered heterocyclic compound. containing a methylene group capable of reacting as described in United States Patent 2,036,546.

In general, the compounds of the present in vention are water insoluble. Their solubility in 7 water. however, is accomplished by the introduction of suitable solubliz ng groups, e. g., sulfonic or carboxylic acid groups into the aryl or heterocycl c nuclei of the above general formula.

The compounds of the present invention when employed as color-formers may be added to the developer, providing they are not fast to diffusion in gelat n. or to the silver-halide emulsion in the form of a solution or a suspension in a suitable solvent. such as 1 N-alcobolic sod um or potassium hydroxide, acetone, ethyl alcohol, isopropyl a cohol. etc. D spersing agents such as isopropyl naphthalene sulfonic acid or any of the dispersing agents disclosed in United States Patent 2,186,717 may be used in prepar ng the suspension of the water insoluble color-formers for incorporation into developers or silver-halide emulsions. Instead of gelatin. the co or-formers may be incorporated in other colloidal mater als, such as, organ c esters of cellulose, super-polyamides. polyesters or synthetic resins. The emulsion may be carried by a transparent medium such .as cellulose esters, super-polyam des. synthetic resins or a non-transparent reflecting medium such as paper, or an opaoue cellulose ester. The emulsion may be coatedas a s ngle layer on the support, or superposed layers containing the couplers may be coated on one. or both sides of the support. The superposed layers may be differentially sensitized for the formation of a color image in the well-known manner.

When incorporating the color-formers into photographic silver-halide emulsions, it is essential that the substitution of the aryl or the fivemembered or six-membered heterocycl c nucleus in the above general formula be such that it will prevent the color-formers from migrating from one layer to another, otherwise color distortion will result upon color-forming development. Several methods have been proposed to prevent migration of color-formers from silver-halide emulsion layers by rendering such color-formers "fast to diffusion in gelatin. This result may be accomplished in several ways. as for example, by substituting the aryl, or the five-membered or six-membered heterocyclic nucleus with suitable groups which impart substantive characteristics to the color-formers which combine permanently with .the gelatin and other colloidal materials of the silver-halide emulsion, or by enlarging the substituent group of the color-former with a long chain alkyl radical so that the color-former is incapable of diffusing from the gelatin or other colloidal material. Examples of such methods which render color-formers fast to d ffusion by imparting substantive characterist cs thereto are disclosed in United States Patent 2179228. Examples of color-formers which are rendered fast to diffusion by enlarging the substituent group are disclosedin Un ted States Pat nts 2.1 8 612; 2,179.244; 2.179.234; 2.179.238-9; 2.179 344; 2.186 045; 2,l86.'719: 2,186. 32-2-4; 2.186 84.9; 2,186,851-2; 2.200.306; 2,280,722; 2.292.575;

2,303,928 and 2,307,399. By reference to the latter patents. it will be noted that the color-formers are modified by the inclusion of radicals of resins. polypeptides, hydrogenated ring systems, carbohydrates, long alkyl chains. and by having the substituent radical recur a number of times in the final molecule. It is to be understood that the substituent group of the color-formers of the present invention, in addition to those previously ment oned. include substantive groups or molecular enlarging groups for the purpose of rendering the arylaldehyde derivatives fast to diffusion.

pmmino-phenols and their substitution products may also be used where the amino group is unsubstituted. All of these compounds are characterized by the presence of a primary amino group in the phenyl nucleus which enables its oxidation product in the developer to couple with the color-forming compound to form a dye image in the emulsion adjacent to the individual particles of the silver image. The silver image may be removed by bleaching in the well-known mans. her to leave the color image in the gelatin layer.

The following example. is illustrative of a suit.- able color developing solution to which the colors formers may be added either as such .or inthe form of a solution in a suitable solvent, such .as ethyl alcohol, 0.1 N=alcoholic potassium hydroxs' ide, acetone and the like, or they may be dissolved in dilute sodium carbonate, sodium or potassium hydroxide solution, c110,, and added to the def veloper prior to color development:

p-Amino-diethylaniline HCl grams 2.0 Sodium carbonate (anhydrousi nudoufl 50.0 Potassium bromide s do 0.2 Water to make liter 1 From the above example, it, will; be seen that the developing solution does not contain sodium sulfite. The presence of this compound is not necessary, since azomethine dyeformation takes place in its absence during color-forming development. However, inorder to. retard the d vel'opine solution from deterioration iby absorp.- tion of oxygen. from the atmosphere. a qu nt ty rangin from 2.. to 5 grams ma he added a preservative. V

Dur ng the course of t e Qolo -for ge lop me it, t e reaction between t a y al de derivative and an oxidized primary amine developing agent, the arylaldehyde derivative splits at the methine chain and is replaced by the nitrogen of the oxidized aromatic primary amine. The reaction with p-dialkyl amino aniline to form an azomethine dye may be pictured in the following manner:

(I) C CHa 1: H i HQN GN Example I z-benzal-fi-methyl-thioindoxyl Equimolar quantities of methyloxythionaphthene and benzaldehyde were dissolved in hot ethanol to which was added several cc. of concentrated HCl. This was allowed to stand overnight. The crystalline substance formed was filteredand recrystallized from glacial acetic acid, and again from" ethanol. A yellow crystalline substance readily soluble in alcoholic KOH was obtained.

One gram of the above product was dissolved in 20 cc. of ethyl alcohol. 2 cc. of the solution was then added to the color developing solution and used for the development of exposed silver-halide emulsion. An excellent magneta dye image was obtained together with the silver image. The latter was readily removed by bleaching.

Erample II Z-benzal-thioindoxyl Equimolar quantities of oxythionaphthene and benzaldehyde were dissolved in hot absolute ethanol. To this solution 3 cc. of concentrated 1101 were added. On standing 14 hours, yellow crystals formed which were filtered off and recrystallized from ethanol.

One gram of the above product was dissolved in 20 cc. of ethyl alcohol. 2 cc. of the solution was then added to the color developing solution and used for the developement of exposed silverhalide emulsion. An excellent magenta dye image was obtained together with the silver image. The silver image was removed by bleaching.

Example III 2- su.liobenzal)-thioindoxyl C O S H Equimolar quantities of oxythionaphthene and m-sulfobenzaldehyde were added to a quantity of aqueous ethanol sufficient to efiect solution. To this was added 3.5 cc. of concentrated HCl and the whole allowed to stand for 2 days. Sufiicient KOH was added to neutralize the hydrochloric acid and the whole evaporated and recrystallized from ethanol.

One gram of the above product was dissolved in 20 cc. of ethyl alcohol. 200. of the solution was then added to the color developing solution and used for the development of exposed silver halide emulsion. An excellent magenta dye image was obtained together with the silver image. The latter was removed by bleaching.

Example 1V 2-(4'-su1fo-5'-stearylaminobenzal)-thiol.ndoxyl 8 NH O 0 01711" Eduimolar quantitiesof oxythionaphthene and 4-sulfo-5-stearylaminobenzaldehyde were added to a quantity of aqueous ethanol suiiicient to effect solution. To this was added 3.5 cc. of concentrated CHl and the whole allowed to stand for Zdays. Sufficient KOH was added to neutralize the hydrochloric acid and the whole evaporated and recrystallized from ethanol.

One gram of the above product was dissolved in 2.0 cc. of l N-alcoholic KOH and added with thorough mixing to cc. of gelatin silver bromide-iodide emulsion. After coating the emulsion containing the color former onto a suitable support and drying, the film was exposed and colordeveloped to yield a magenta dye image together with the silver image. The latter was removed by bleaching in the well-known manner.

N-C O I H SOaH One gram of the above compound obtained according to Example VI of United States Patent 2,036,546 was dissolved in a small quantity of a 5% sodium carbonate solution. This solution was added to the color developing solution of an exposed silver halide emulsion. An excellent cyan dye image was obtained together with the silver image. The silver image was removed by bleaching in the well-known manner.

While We have disclosed the preferred embodiments of our invention and the preferred. modes of carrying the same into effect, it will be readily apparent to those skilled in the art that many variations may be made therein without departing from the spirit and scope thereof. Accordingly, the scope of our invention is to be limited only by the following claims.

We claim:

1. A color-forming photographic developer comprising an aromatic primary amino developing agent and a coupler compound of the formula:

wherein R. represents the atoms necessary to complete a six-membered isocyclic ring, and R1 represents an aromatic radical.

2. A method of producing a dye image in a gelatino silver halide emulsion which comprises exposing the emulsion and developing it with an aromatic primary amino developing agent in the presence of a coupler compound of the formula:

Wherein R represents the atoms necessary to complete a six-membered isocyclic ring, and R1 represents an aromatic radical.

3. A color-forming photographic developer comprising an aromatic primary amino developing agent and 2-(3'-sulfobenzal)-thioindoxyl.

4. A color-forming photographic developer comprising an aromatic primary amino develop- FRITZ W. H. MUELLER. ABRAHAM BAVLEY.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,036,546 Schneider Apr. 7, 1936 2,133,937 Middleton et a1 Oct. 18, 1938 2,186,849 Wiemanns et al Jan. 9, 1940 2,213,986 Kendall Sept. 10, 1940 2,220,123 Schwarc Nov. 5, 1940 2,274,782 Gaspar Mar. 3, 1942 2,397,865 Jennings Apr. 2,1946 2,397,867 Jennings Apr. 2, 1946 FOREIGN PATENTS Number Country Date 481,274 Great Britain Mar. 8, 1938 513,596 Great Britain Oct. 17,1939

OTHER REFERENCES Beilstein, Handbuch der Organischen Chemie,

'20 4th edition, vol. XXVI/XXVII, first supplement 1938, page 301 cited. 

